<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8" />
  <title>Hello World</title>
  <script src="https://unpkg.com/react@16/umd/react.development.js"></script>
  <script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
  <script src="https://unpkg.com/babel-standalone@6.15.0/babel.min.js"></script>
  <style>
    body{
      padding:5px;
    }

    .red{
      color:red;
    }
  </style>
</head>

<body>
  <div id="root"></div>
  <!-- <script type="text/babel" src="./CustomButton.js"></script> -->
  <script type="text/babel">

  function CustomTextInput(props){
    let textInput = null;

    function handleClick(){
      textInput.focus();
    }
    
    return (
      <div>
        <input type="text" ref={(input) => {textInput = input;}}/>
        <input type="button" value="Foucs the text input" onClick={handleClick}/>
      </div>
    );
  }

  ReactDOM.render(<CustomTextInput/>,document.getElementById('root'));

  </script>
  <!--
      Note: this page is a great way to try React but it's not suitable for production.
      It slowly compiles JSX with Babel in the browser and uses a large development build of React.

      To set up a production-ready React build environment, follow these instructions:
      * https://reactjs.org/docs/add-react-to-a-new-app.html
      * https://reactjs.org/docs/add-react-to-an-existing-app.html

      You can also use React without JSX, in which case you can remove Babel:
      * https://reactjs.org/docs/react-without-jsx.html
      * https://reactjs.org/docs/cdn-links.html
    -->
</body>

</html>